The invention relates to in-line or tandem roller skates and comprises a lighter, faster, and more smoothly operating in-line roller skate which is easily manufactured and more durable under both normal and extreme operating conditions including hot weather and heavy, sustained use by large adults.
In-line roller skates utilize two or more wheels positioned to rotate within a common, vertical plane and while operating as roller skates have much of the feel and behavior associated with ice skates. Substantially the same bodily movements are required to operate both ice and in-line roller skates, and such roller skates have become increasingly popular with ice skaters as a desirable training tool for off season and on-street use. In recent years, they have been capturing an increasing share of the recreational skate market and in time may parallel jogging as a healthy and pleasurable adult sport.
Tandem skates are well known and appear at least as early as 1876 in U.S. Pat. No. 7,345 of C. W. Saladee, which disclosed a two-wheel in-line model featuring a somewhat complex, spring loaded carriage supporting laterally pivoting rollers for improved maneuverability and even distribution of skater weight but was heavy, noisy and quite complicated to manufacture and assemble.
In 1946, U.S. Pat. No. 2,412,290 to O. G. Roeske disclosed a heavy metal framed, three-wheel, in-line skate for indoor use which featured an endless, rubberized belt so as to avoid damage to wooden floors. The belt rotated on three pulley-like wheels wherein the intermediate wheel was vertically adjustable to produce a rocking action in a forward or rearward direction which made it easier to steer and manuever the skate. Vertical adjustment of the intermediate wheel was achieved by a clamping bolt and a system of interlocking teeth and allowed a range of vertical adjustment.
In 1966, G. K. Ware in U.S. Pat. No. 3,287,023 disclosed an in-line skate with thin, rounded wheels which endeavored to simulate the performance of ice skates. The Ware skate utilized a fairly heavy metal frame having front and rear frame members with longitudinally extending and overlapping sections. These sections had a multiplicity of horizontally arranged axle apertures which permitted positioning of wheel axles in a variety of different locations and provided continuous adjustability of the frame to accommodate a wide variety of boot sizes. The Ware frame also included the positioning of apertures at several elevations at the front and rear of the skate so that the forward and rear wheels could be at a higher level than the two intermediate wheels. The Ware frame and variations of it are still in use on currently available in-line roller skates and has been the best all around frame available for such skates.
The Ware skate utilized a wheel formed of tough, firm but slightly soft and resilient rubber and having a central hub into which individual ball bearings were received and in which they were retained by a pair of cone elements which extended laterally from the wheel, so as to prevent contact between wheel and frame during cornering of the skate. A toe brake was utilized at the front end of the skate for stopping the skate.
U.S. Pat. No. 4,492,385 to Scott B. Olson disclosed a hybrid skate combining the desirable features of both ice and roller skates and featured a mounting system which could carry either the traditional ice skating blade or a series of in-line wheels.
Other tandem roller skates with various wheel structures and configurations are shown in U.S. Pat. Nos. 3,880,441, 3,900,203, 3,963,252, and 4,618,158. A number of distinct wheel structures have been developed for use with tandem skates, conventional roller skates and other roller devices, some of which are shown in U.S. Pat. Nos. 189,783, 2,670,242, 4,054,335 and 4,114,952.
As best shown in FIGS. 1 and 2, currently available in-line skates use a rigid, heavy metal Ware style frame 33P, which is fixed to a boot 13P and used for support of the wheels 10P. The best presently available wheels utilize an outer urethane tire member 12P which is molded about an inner, one piece hub 14P which retains left and right bearings 42P and 44P, respectively, and rotates about those bearings. The outer, annular tire member 12P is formed of relatively elastic, resilient, urethane material and closely encapsulates much of the central hub 14P. This wheel 10P, with its centrally positioned, internal hub 14P has tended to overheat during heavy use, and the urethane adjacent the hub sometimes melts and separates from the hub during sustained high speed, warm weather operation.
The hub 14P, as best shown in FIG. 2, is formed of a nylon material and has an outer annular ring 16P which is substantially concentric with an inner ring 18P, rings 16P and 18P being interconnected by four radially extending vanes 20P, which are centered on and lie within a plane 22P (FIG. 1) which vertically bisects the wheel 10P and is perpendicular to the hub's central axis 64P. The centrally positioned vanes 20P are separated by substantially equal sectors of arc and are closely surrounded and encapsulated within the urethane material of the tire member, the urethane extending through the open sectors between the vanes 20P. Left and right bearing apertures 26P and 28P are formed within the open ends of inner ring 18P and are separated by an intervening shoulder 30P, which is molded into the inner periphery of ring 18P.
Each wheel 10P is rotatably mounted between metal side rails 32P and 34P of the skate's heavy metal frame by threaded axle 36P, which passes through axle apertures 38P in the side rails. Washers 40P are positioned against the outer face of each of the bearings 42P and 44P and contact the side rails of the frame. A cylindrical metal spacer 46P is retained on axle 36P between bearings 42P and 44P. With the axle 36P inserted through the described components, as shown in FIGS. 1 and 2, and the nut 48P tightened on the threaded end of the axle, the bearings 42P and 44P have their inner races 50P tightly clamped between the washers 40P and the spacer 46P, so as to allow the outer race 52P of each bearing to rotate freely about the inner race 50P.
While the wheel 10P has better overall performance than earlier wheels, under prolonged and steady use during warm weather, and particularly by heavy skaters at high speeds, the urethane material in the areas 54P (FIG. 1A) adjacent the outer periphery of ring 18P would heat up to a temperature where the urethane would melt and begin separating from the ring 18P, thereby causing failure and eventual collapse of the wheel. This problem requires a solution which does not involve substantially changing the otherwise highly desirable and well performing urethane material from which the tire member has been formed. Providing a working solution has been further complicated by the fact that heat buildup at the melting area came in differing amounts from several sources, including the bearings themselves, from heat generated at the wheels, outer periphery by rolling friction, from heat produced by the constant flexing of the resilient tire member 12P during riding, and from heat from asphalt or concrete riding surfaces on which the wheels rotated and which in hot, sunny weather could reach temperatures in excess of 120.degree. F.
Investigation and study by the inventor has led to the conclusion that the overheating and melting of the urethane tire member 12P is attributable principally to the arrangement of the central vanes 20P on hub 14P. When the wheel 10P rotates on a nonlevel surface, such as surface 56P (FIG. 1), the resilient urethane material of the tire member 12P tends to deform and shape itself to fit the contour of surface 56P and bulges outwardly at 58P. This bulging action generates internal forces within the urethane tire member, and as best shown in FIG. 1A, can generate a force couple 60P which can cause the outer ring 16P to cant in the direction of the force couple. This force couple 60P is transmitted along the ring 16P and through the vanes 20P to be transferred with some attenuation to inner ring 18P through vanes 20P to distort hub 14P and generate forces 62P which are applied to the bearings 42P and 44P and cause canting of the outer races 52P relative to the inner races 50P, thereby increasing the friction between inner and outer races and causing undesirable heat buildup in the bearings. The canting problem is shown in an exaggerated form in FIG. 1A for ease of visual perception. As best understood from an examination of FIG. 1A, when the outer races 52P of the bearings are cammed out of alignment, the side seals 72P and 66P on inner and outer side surfaces of the bearings are stretched or compressed. The outer side seal 66P of bearing 42P is placed in tension in area 68P below axle 36P and in compression at area 70P above the axle. Similarly, on the inner side of bearing 42P, inner seal 72P is placed in compression in area 74P below the axle and in compression in area 76P above the axle.
Similarly, bearing 44P has its outer seal 66P deformed by the canting effects with seal area 78P below the axle being placed in compression and seal area 80P above the axle being in tension. The inner seal 72P of bearing 44P is under tension at area 84P below the axle and under compression at area 86P above the axle.
The canting of the outer races and the deforming of the inner and outer bearing seals is not in practice as extreme as shown in FIG. 1A, which is exaggerated so as to permit visual perception of the problem, but such deformation is sufficient to increase friction in the bearings 42P and 44P to unacceptable levels which produce sufficient heat to melt the urethane tire members. This heat is transferred from the outer periphery of the bearing and through the thickness of inner ring 18P, which contacts the bearing, to finally heat regions 54P of the tire member to melting levels. It should be understood that this overheating problem is at its worst when the tire member is already at a high temperature from prolonged running on a hot, sun heated riding surface and when the skates carry an exceptionally heavy skater. Prolonged use of the skate over many miles of surface will further increase the heat buildup. Under extreme conditions, even the urethane surrounding outer ring 16P will melt and deteriorate.
It is desirable to provide an improved hub which avoids such overheating and is capable of high speed, heavy duty, sustained, warm weather operation by even heavy adult users on nonlevel surfaces. It is particularly important to avoid overheating caused by nonlevel surface conditions since most skating is done on nonlevel surfaces. It is relatively rare to find precisely level, flat riding surfaces and normally because of the uneven surfaces of sidewalks, streets, and the inclination of most paved surfaces for drainage, skate wheels will almost always be operating on nonlevel surfaces which apply forces which would distort the outer ring 16P of the hub 14P and normally generate varying magnitudes of unwanted canting forces which, under heavy loading, sustained riding situations, produce overheating and wheel breakdown.
Some conventional roller skates with side by side wheels have utilized hubs with inner and outer concentric rings where the outer ring is positioned adjacent the outer end of the inner ring. It is known to utilize radially positioned vanes extending between such off-centered rings and to have the vanes in planes parallel to and passing through the central axis of the concentric rings. Such an arrangement is satisfactory for the wide, rectangular cross sections of conventional roller skates but would not be usable with or function well with the thinner, rounded, in-line wheels which often operate at an angle to the riding surface.
A second shortcoming associated with presently available in-line skates is the excessive time and labor required to install or replace individual wheels. To install a new wheel on a standard metal frame 33P, like that shown in FIGS. 1 and 2, the assembler first places bearing spacer 46P within inner ring 18P and then inserts bearings 42P and 44P into apertures 26P and 28P of the hub. When the assembler thereafter attempts to insert the axle 36P through the bearings and spacer 46P, the spacer 46P will frequently have its central aperture 47P off center from the bearings, thereby making it difficult to slide the axle 36P through the wheel. To insert the axle, the assembler must manipulate the spacer with an appropriate tool or rotate the wheel about its axis to .work the bearing spacer into a centered position where the axle can pass cleanly through the open center 47P of the spacer. Because the axle insertion must be done with the wheel 10P already positioned between the side rails 33P and 34P, the assembler's job is further complicated by having reduced visibility of the bearings and the need to simultaneously manipulate the entire skate frame 33P. Since each skate generally has three or four wheels, the alignment problem is encountered repeatedly and must be overcome with each wheel.
The axle alignment and insertion problem is further complicated by the difficulty of inserting the axle through a frame side rail and then aligning the spacing washer 40P which contacts the outer face of the bearing so as to permit insertion of the axle through the washer. The problem occurs again when a second washer 40P is encountered on the far side of hub 14P. Typically, the washers are difficult to keep in an orientation coaxial with the axle and, consequently, the assembler must try to manipulate the washer into position by manipulating the skate frame or inserting a small tool to move the washer about in the relatively close spacing between side rails and bearing. The collective assembly problem posed by aligning the two loose washers 40P, the bearings 42P and 44P and the loose bearing spacer 46P results in slower assembly for each of the three or four wheels on the skate, and is encountered again when a wheel must be removed for service or replacement. It is desirable to eliminate this assembly problem without adversely affecting the strength, weight, speed or smoothness of the skate's operation.
A third shortcoming of presently available skates is the heavy, metal, Ware style frame up to now required for prolonged, safe operation. While the heavy metal skate frames function acceptably, they are unattractive, susceptible to rusting, pose assembly problems and can cause scratching and marring of surfaces that are struck by the skate. The Ware style frames have multiple axle apertures arranged along the sides of the frame to assure a proper spacing for all axles when the two part frame is adjusted to the length of the boot. The Ware frame also has alternate axle apertures to allow the axles at the front and rear ends of the skate to be placed at either the same elevation as the intermediate wheels or at a slightly higher level. These many apertures, most of which are not used and are located between the actually utilized apertures, detract from the aesthetic appearance of the skate and further complicate the overall assembly of the skate frame and the installation of wheels and axles insofar as the additional apertures sometimes confuse assemblers and the axles must pass through an additional set of aligned holes in the two section frame, and any minor misalignment between confronting apertures slows up assembly.
Replacement of the hard, rigid metal frame with a lighter synthetic frame would also make the frame safer insofar as collisions between skaters and pedestrians will produce less harm when a lighter synthetic frame is used. When the skate is used indoors, elimination of the metal frame will also reduce scratching and scuffing of floors, furniture and the like.
Accordingly, it is desirable to eliminate the metal, multiple apertured, rigid frame and replace it with a lighter, more aesthetically pleasing, one piece frame which is safer, more economical to manufacture, is noncorroding and permits more rapid and simplified assembly.
In an effort to provide a faster and safer skate, it is also desirable to eliminate the hard, rigid metal frame of the known brake assembly and to replace it with a lighter, more smoothly contoured and safer synthetic brake assembly. Currently available skates have a brake attached to and extending rearwardly from the metal skate frame and consisting of a metal flange to which is attached a downwardly depending brake pad. The pad has a central threaded stud which is affixed to the metal flange with a locking nut and screw. To replace the old metal structure with a lighter but safe brake assembly formed of synthetic material, it is essential that the strength of the brake assembly be adequate for all stopping purposes and that the synthetic components be designed to withstand sheer forces and strains.